1. Field of the Invention
The present invention is related to a device control system for controlling a device appliance by transmitting/receiving a signal between a host appliance and the device appliance.
2. Description of the Related Art
Recently, there are many cases that the USB (Universal Serial Bus) standard has been employed as serial interfaces utilized in data communications and so on. This USB standard is employed so as to transmit/receive communication data between, for instance, a personal computer and a modem. Also, for example, in the case that a FAX apparatus (facsimile machine) functioning as a built-in type device appliance which is built in a copy machine is connected to a control apparatus of the copy machine functioning as a host appliance, this USB standard may be sometimes used.
In an electronic appliance employing a USB interfaces, in the case that the USB interface happens to hang up, a power supply of this USB interface is interrupted (cut out) and thereafter is again turned ON so as to reinitiate the USB interface, so that the entire electronic appliance is recovered. However, in accordance with this reinitiating method, for example, in the case that a built-in type appliance is used, while there is a certain possibility that a device appliance and a host appliance commonly use a power supply unit, a power supply for driving the device appliance and a power supply for driving the host appliance must be cut out all together in order to reinitiate a USB interface employed in such a built-in type appliance.
Also, when the power supply of the USB interface is cut out, since a communication from the host appliance to the device appliance cannot be performed, the power supply of the USB interface must be maintained under ON state even while the device appliance is controlled in a power saving mode and thus a power supply of a partial circuit portion thereof is cut out. As a result, a power saving efficiency becomes lower.
As previously described, in the conventional device control system, the recovery operation for such a case that the USB interface happens to hang up becomes cumbersome and the utility thereof is low. For instance, in the case that a built-in type electronic appliance employs such a USB interface, when a power supply is cut out, there are some possibilities that a power supply of an entire system must be interrupted, resulting in low utility. Also, since the supply of electric power to the USB interface cannot be stopped in order to accept the communications even while the device appliance is controlled in the power saving mode, the power saving efficiency becomes low.